Check out gardenweb.com - A member there by the name of "tapla" is basically a genius when it comes to that stuff. He has an entire thesis on containerized soil culture and recommends numerous potting soil blends that really work... I know from personal experience in using them.
Here's one of them from memory:
Basic soil:
5 parts pine bark fines (partially composted fines are best)
1 part sphagnum peat (not reed or sedge peat)
1-2 parts perlite
garden lime (or gypsum in some cases)
control-release fertilizer, as directed
micro-nutrient formula, other source of micro-nutrients, or fertilizer with all nutrients - including minors